Good move.
Round up every bundle of concertina that can be found in the country and ship it to the border.
Having personally seen the Berlin Wall from both sides in 1971, one could not help but be impressed by how thorough its construction was. Carefully planned and constructed. It WORKED. Few got across it and lived to tell about it.
But -- it wasn't "built in a day".
The East Germans started simply -- again, with barbed wire and guards -- and "built up" from there.
So it should be with the southern border.
Get that wire up.
Then work on more substantial and more permanent barriers.